Browse Definitions :
Definition

logic level

A logic level is one of several states that a digital signal can possess, expressed as a DC (direct-current) voltage with respect to electrical ground. Usually, the term refers to binary logic in which two levels, or states, can exist: logic 1 (also called the high state) and logic 0 (also called the low state).

In most circuits, logic 1 is represented by approximately +5 V (positive 5 volts) relative to ground, while logic 0 is represented by approximately the same voltage as ground (0 V). This system is called positive or active-high logic. In some circuits the two voltage levels are reversed, so that the higher voltage represents logic 0 and the lower voltage represents logic 1. This system is known as negative or active-low logic.

In most practical systems, there is some room for error in the logic voltages. For example, in an active-high circuit, logic 1 might be represented by any voltage between +3.5 V and +6.5 V, while logic 0 might be represented by any voltage between -1.0 V and +2.0 V. A signal between +2.0 V and +3.5 V would not be recognized as either low or high, and would be rejected as invalid.

In practical binary circuits, logic levels are handled and manipulated by electronic switches, called logic gates, connected in massive arrays to perform digital calculations and operations. Binary logic serves as the basis on which nearly all digital devices, including computers, operate.

Some circuits work with more than two digital levels. A system based on trinary logic has three levels, representing digits or states called -1 (false), 0 (neutral), and +1 (true); most others have some higher power of two levels, such as four, eight, 16, 32, 64, and so on.

This was last updated in October 2012
SearchCompliance
  • compliance risk

    Compliance risk is an organization's potential exposure to legal penalties, financial forfeiture and material loss, resulting ...

  • information governance

    Information governance is a holistic approach to managing corporate information by implementing processes, roles, controls and ...

  • enterprise document management (EDM)

    Enterprise document management (EDM) is a strategy for overseeing an organization's paper and electronic documents so they can be...

SearchSecurity
  • session key

    A session key is an encryption and decryption key that is randomly generated to ensure the security of a communications session ...

  • computer forensics (cyber forensics)

    Computer forensics is the application of investigation and analysis techniques to gather and preserve evidence from a particular ...

  • multifactor authentication (MFA)

    Multifactor authentication (MFA) is a security technology that requires more than one method of authentication from independent ...

SearchHealthIT
SearchDisasterRecovery
  • risk mitigation

    Risk mitigation is a strategy to prepare for and lessen the effects of threats faced by a business.

  • call tree

    A call tree is a layered hierarchical communication model that is used to notify specific individuals of an event and coordinate ...

  • Disaster Recovery as a Service (DRaaS)

    Disaster recovery as a service (DRaaS) is the replication and hosting of physical or virtual servers by a third party to provide ...

SearchStorage
  • cloud storage

    Cloud storage is a service model in which data is transmitted and stored on remote storage systems, where it is maintained, ...

  • cloud testing

    Cloud testing is the process of using the cloud computing resources of a third-party service provider to test software ...

  • storage virtualization

    Storage virtualization is the pooling of physical storage from multiple storage devices into what appears to be a single storage ...

Close